Synthesis of substituted pteridins



Patented Feb 1 7, 948

r or ies SYNWSKS F SUBSTITUTED .PTERIDEN S John E. Mowat, Pearl River, N. Y assignor, by

means assignments, to American Cyanamid Company, New York, N. H... a corporation or in? sin;

No ilirawina. Application November 29, 1945.

, Serial No. 631,787

. F con q T NQ BK 21110 NHu-L in which X is halogen and R is -OH, OR' or NR" R', It being an alkyl radical and R" and R" being hydrogen, aliphatic or aromatic radicals.

Generally speaking, the compounds prepared by the process of the present invention are yellow to reddish-brown crystalline solids, dimcultly soluble in water and organic solvents, Some possessvitamin-like properties and appear to be necessary for, or stimulate the growth of, certain bacteria and higher forms of animal life. Some are also useful in stimulating haemoglobin formation and in the treatment of agranulocytosis.

' Some of the compounds which may be prepared 8 Malina. (Cl. 260-251) etc. Whether or not the compound exists in the I esters of p-aminobenzoic acid, such as the methyl keto form or the enol form probably depends upon the pH of the medium in which it is dissolved. In acid media the compound most likely exists in keto form whereas in alkaline media it emsts as the enol form. It will also be noted that the Z-amino group may also be tautomeric with an imino group. As will be understood by those in the art. any of thetautomeric-forms may be used in the same chemical reactions in like manner and reference hereinafter to the use or one tautomeric form includes the use of the others. 0bviously, the final product may exhibit the same kind of tautomerism.

The referred halopyruvic aldehyde is bromopyruvic aldehyde. although other halopyruvic aidehydes can be used, such as chloropyruvic aldehyde. It will also be noted that acetals of halopyruvic aldehydes may be used in the reaction. As an equilibrium exists between the free aldehyde and its acetal in solution, it is believed that the actual reactant is the aldehyde itself. Accordingly, when reference is made hereinafter, and in the claims, to the use of a halopyruvic aldehyde. such reference is intended to include the equivalent use of the corresponding halopyruvic aldehyde acetals. inasmuch as these halopyruvio aldehydes and acetals appear to be new a method of preparing them is described herein.

The aminobenzoyl reactants include any ortho, meta, or para-aminobenzoic acid, and salts, esters, and amides and other related derivatives thereof. The biological activity of the resulting product depends. in large measure, upon the particular aminobenzoyl compound employed in the reaction. For example, when p-aminobenzoic acid or its .salts are used, the resulting product is biologically active as an essential growth factor for Streptococcus fecdlis R but is, however, inactive with certain other organisms for which other compounds of the invention show activity.

The compounds that. are formed when using ethyl, butyl, benzyl, and the like, esters, do not appear to possess the same biological activity, being inefiective in promoting the growth of Streptococcus fecalz's R and certain other organisms with which these compounds have been tested at the present time. It is possible, however, that these particular compounds may be of value in experimental medicine in other ways.

An important group of compounds prepared by the process of thepresent invention are those obtained when using as intermediates the amides oi aminobenzoic acid. These intermediates in 3 elude ortho, meta. and para-aminobenzamide and other amides in which R" and/or R', in the general formula, may be hydrogen, aliphatic, or aromatic radicals, such as ethyl, ethanol, dodecyi, ethylhexyl, benzyl, phenyl, etc., or those in which R" and R' together form a closed ring.

Of the various aminobenzoic acid amides that may be employed as intermediates, the most important appear to be those amino acids, parabsolute ethanol and added to a hot (90 0.) solution of 1 g. 0! para-aminobenzoylglutamic acid and 1 g. of sodium carbonate in 20 cc. of water. A portion or the cooled solution was then reacted with an aqueous solution 0! 2.4,5-trlamino-B-hydroxypyrimidine. The mixture was acidified with acetic acid and allowed to stand at room temperature for one hour. The product obtained was biologically active and had the 01- glycine, aspartic acid, leucine, alanine, isovaline,

cysteine, and the like, are also important intermediates of thepresent invention. The amino acids may be natural or synthetic and may be in any of the d, 1, or dl forms. As these amino acid amides possess free carboxyl groups, it will be apparent that the salts and esters thereof 'may likewise be employed.

The reaction may be conducted by mixing all of .the three essential retactants together at the same time or the halopyruvicaldehyde may be first reacted with one of the other two reactants before adding the third to the reaction mixture.

Thereaction may take place over a wide range of temperatures, from about 0. up to 100 C. or higher. Likewise, the reaction will take place .under a wide range of pH conditions, there appearing to be no limiting acidity or alkalinity.

Best results appear to be obtained, however, within the range of pH 3 to pH 5.

a The reaction is usually conducted with the reactants dissolved or suspended in a solvent such as water, ethyl alcohol, acetone, benzene, carbon- ,tetrachloride, chloroform, etc. or mixtures thereof.

The invention will now be described in greater particularity by means of the following examples in which various reaction conditions are illustrated.

Example 1 A solution oi. 13 g. ethyl wy-diethoxy aceto acetate in 68 cc. of 1 N potassium hydroxide was refluxed for about minutes. The mixture was then extracted with ether and the dried ethereal solution was evaporated to remove ether. The oily residue was then fractionated in vacuo. A yield of 5.25 g. of pyruvic aldehyde acetal, boiling point 67-68 C. at mm./Hg, was obtained.

To a, well stirred mixture of 1 g. pyruvio aldehyde acetal, 1 g. of anhydrous sodium carbonate and 10 cc. of carbon disulphide was added a solution of 0.352 cc. of bromine in 4 cc. of carbon disulphide. When all of the bromine had reacted the solution was decanted from the sodium salts and evaporated in vacuo. The residue was taken up in dry ether and washed with a little sodium bicarbonate solution. The ether solution was then dried and evaporated in vacuo. The residual oil was distilled in vacuo in a molecular still. The product obtained was bromopyruvic aldehyde acetal.

The bromo compound obtained from 0.5 g. of

pyruvic aldehyde acetal was dissolved in a little fTTas isa H N N i 1 :1

lowing formula:

coon N-[4-{- (2-amino-4-hydroxy-6-pyrimid0 [4, 5- blpyrazyl) methyll-amino}-benzoyll glutamic acid is the name given this material under the Ring Index system of naming.

Example 2 hour. At the end 0! that time an aqueous solution of 2,4,5-triamino-6-hydroxy-pyrimidine was added. The product was found to be eflfective in stimulating the growth of Streptococcus Iecalia R. and Lactobacillus casei. It was found to be identical with product obtained in Example 1.

Example 3 A solution of 0.6 g. of para-aminobenzoyldlethylglutamate in 10 cc. of warm absolute ethanol was treated with a solution of 0.202 g. of distilled bromopyruvic aldehyde acetal in 1 cc. of absolute alcohol, and the mixture was heated on the steam bath under reflux conditions for about 10 minutes. After removing two-thirds of the alcohol in vacuo, the cooled residual solution was then treated with a solution of 0.13 g. of 2,4,5-triamino-6-hydroxypyrimidine in 10 cc. of water and 0.5 cc. of glacial acetic acid. The mixture was warmed for a few minutes and then allowed to stand at room temperature for six hours. The pH of the mixture was about 3-4.

The reaction mixture which contained considerable brownish precipitate was made up to 25 cc. volume with water. A 20 cc. portion of this mixture was centrifuged and the solid was then dissolved in warm, dilute alkali and reprecipitated at about ph 3 with hydrochloric acid. The precipitate was washed with water, alcohol and ether. The product was the same as that of Example 1.

Example 4 2-3 cc. of ethanol was added to increase the solubility of the acetal. Ai'ter 2 hours at room temperature the mixture was made alkaline with sodium hydroxide and then acidified to pH of radicalsin which a is or. alkyl a about 2 with hydrochloric acid. The precipitate was collected, washed with water, alcohol and ether. The product was identical with that of Example 1.

As previously stated, identical products are obtained when using the halopyruvicaldehyde in place of the acetal and when using the tautomeric 2,4,5-triaminopyrimidone-6 in place of 2,4,5- triamino-fi-hydroxypyrlmidine. i

Related products are obtained when using other aminobenzoyl derivatives in place of paraaminobenzoylglutamic acid in the process of the preceeding examples.

I claim:

1. The method which comprises mixing together in a solvent 2,4,5-triamiuo-6-hydroxy pyrimidine, a member of the group consisting of halopyruvic aldehyde and acetals thereof. and a member of the group consisting of aminobenzoic acid and its salts, esters and amides thereof and after reaction recovering the resulting pterin.

2. A method of preparing compounds havin the general formula:

COR

in which R is a member of the group consistmg of the general formula:

on can N mu in which R is a member of the groupconsist- -'on.-on',mdN

radical audit" and R'" are hydrogen, aromatic or aliphatic radicals which comprises mixing together in a solvent 2,4,5-triamino-6-hydroxypyrimidine and a member of the group consisting of halopyruvic aldehyde and acetals thereof, and thereafter addme to the reaction mixture 9. member of the group consisting of aminobenzoic acid and salts.

on a

N q IcmNnO-coa NHr-L I N N in which R is a member of the group consisting which the amide of p-anunobenaoic acid m radicals in which R is an alkyl radical and R" and R' are hydrogen. aliphatic or aromatic radicals which comprises mixing together in a solvent a member of the group consisting of halo= pyruvic aldehyde and acetals thereof and a member of the group consisting of aminobenaolc acid and salts, esters. and amides thereof and there after adding to the reaction mixture 2.4.5-triamino-G-hydroxypyrimidine and after reaction thereof recovering a pterin having the said formula. w

5. A method ,of preparing compounds having the general formula: I

-on, -oa'. and

radicals which comprises mixing together in a solventat a pH within the range of about 3 to 5 2,4.5-triamino-d-hydrorypyrixnidine. a halopyruvic aldehyde and an amide of p-aminobenzoic acid. heating the mixture and after reaction thereof recovering a pterin having the said formula. v CI V 6.'A method in accordance with claim 5 in love aminobenzoyl-alutamic acid; I I. A method in accordance with claim which the amide of p-aminobenzoicacid .is

aminobenzoyl-aspartic' acid. I

in p- 8. A method, in accordance with claimo-in which the amide ofup-aminobenooic acid is p aminobenzoyl-glutamrlglutamic acid.

come a. slower. t 

